1. Field of the Invention
The present invention relates to an object, a method, or a manufacturing method. In addition, the present invention relates to a process, a machine, manufacture, or a composition of matter. In particular, one embodiment of the present invention relates to a semiconductor device, a display device, a light-emitting device, a power storage device, a driving method thereof, or a manufacturing method thereof. In particular, one embodiment of the present invention relates to a multi-gate transistor or a semiconductor device with a multi-gate transistor.
Note that in this specification or the like, a semiconductor device refers to any device that can function by utilizing semiconductor characteristics. A semiconductor element such as a transistor, a semiconductor circuit, an arithmetic device, and a memory device are each an embodiment of a semiconductor device. An imaging device, a display device, a liquid crystal display device, a light-emitting device, an electro-optical device, a power generation device (including a thin film solar cell, an organic thin film solar cell, and the like), a high-voltage device having higher withstand voltage than silicon, an integrated circuit or power supply circuit or power converter circuit with the high-voltage device, and an electronic appliance may have a semiconductor device.
2. Description of the Related Art
A technique by which transistors are formed using semiconductor thin films formed over a substrate having an insulating surface has been attracting attention. The transistor is used in a wide range of electronic devices such as an integrated circuit (IC) or an image display device (also simply referred to as a display device). As semiconductor thin films that can be used for the transistors, silicon-based semiconductor materials have been widely known, but oxide semiconductors have been attracting attention as alternative materials.
A transistor using an oxide semiconductor material has small off-state current. Thus, a potential of a node (the amount of charge held in the node) which is brought into a floating state when the transistor is turned off can be held for a long time. Accordingly, it is expected that a memory device is fabricated using the transistor. For example, Patent Document 1 discloses a memory device with a dynamic random access memory (DRAM) including the transistor in a memory cell.